Ink composition for ink jet recording, ink supply system, and ink jet recording apparatus

ABSTRACT

There is provided an ink composition which has excellent initial filling characteristics and continuous printing stability even in a case of an ink composition (for example, dissolved nitrogen is equal to or greater than 5 ppm) which is almost not deaerated or an ink composition (for example, dissolved nitrogen is equal to or greater than 7 ppm) which is not deaerated at all. 
     The ink composition includes an alkylene oxide adduct (A) of acetylenic glycol in which a main chain has 12 or more carbon atoms, acetylenic glycol (B) in which a main chain has 10 or more carbon atoms, and polyoxyalkylene alkyl ether (C).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase application ofPCT/JP2013/056813, filed on Mar. 12, 2013, and published in Japanese asWO 2013/161410 A1 on Oct. 31, 2013. This application is based upon andclaims the benefit of priority from Japanese Patent Application No.2012-097538, filed on Apr. 23, 2012 and Japanese Patent Application No.2012-097540 filed on Apr. 23, 2012; the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an ink composition for ink jetrecording. In addition, the present invention relates to an ink supplysystem and an ink jet recording apparatus provided with the same.

BACKGROUND ART

In the related art, a printing method, which uses an ink jet recordingmethod, discharges and causes small ink droplets to fly from a printhead, and attaches the ink droplets onto a recording medium, such as apaper sheet. At a time of discharging ink, a discharging failure tendsto occur due to bubbles generated in the ink. Here, varioustechnologies, which eliminate the bubbles and stably discharge the inkdroplets by using a deaerator or the like and deaerating the ink, havebeen suggested.

For example, JP-A-2011-42104 discloses deaerated ink (air decompressionrate of a film deaeration module is −90 kPA, and dissolved oxygen of theink at a module outlet is 1.86 ppm (20° C.)) which is made by deaeratingcyan ink made of 13 mass % of reactive and water-soluble dye (C. IReactive Blue 72), 60 mass % of ion exchanged water, 23.7 mass % ofethylene glycol, 0.3 mass % of surfactant (Olefin E 1010:acetylenicglycol-based surfactant manufactured by Nissin Chemical Industry Co.,Ltd.), and 2 mass % of anti-mold agent (Proxel GXL-S manufactured byArch Chemicals Co., Ltd.), by using a film deaeration module (externalrefluxing type, EF-G3 manufactured by DIC Co., Ltd) (refer to paragraphs0120 and 0124 in JP-A-2011-42104).

In addition, for example, as an ink supply method to the print head, amethod of supplying the ink to the print head which is attached to aprinter via a tube from an ink outlet portion of an ink tank, isdisclosed (for example, JP-A-2011-4210 and JP-T-11-504874). According tothe ink supply method disclosed in JP-A-2011-42104 and JP-T-11-504874,the ink tank is provided with a liquid pouring path (hereinafter,referred to as an “ink filling port”, or a “liquid pouring portion”),and a user can easily pour the ink from the liquid pouring path.

SUMMARY OF INVENTION Technical Problem

However, a first problem is that an ink tank which is available on themarket is relatively cheap, but the ink and the atmosphere may come intocontact with each other according to the structure thereof. In addition,in a general open type cartridge as an ink cartridge which is availableon the market, the air gradually dissolves into the ink even whendeaerated ink is filled. When the deaerated ink which is disclosed inJP-A-2011-42104 goes through the ink tank or the open type cartridge,the air dissolves into the ink, and thus, deaeration is of no use and aproblem of a discharging failure occurs.

In addition, a second problem is that, according to the ink supplymethod disclosed in JP-T-11-504874 and JP-A-2003-127427, the air isintroduced into the ink tank from the air introducing port of the inktank as the ink is supplied to the print head side from the ink tank.Here, depending on a position of the air introducing port forintroducing the air into the ink tank, there is a case where the air(bubbles) passes through the ink and is introduced into the ink tank.Examples of this case include a case where the air introducing path forintroducing the air is provided and an ink storage container having astructure which generates bubbles in the ink is used. In this case, whenthe bubbles flow out of the ink tank together with the ink and arecarried to the print head, a problem of a filling failure or adischarging failure in the print head occurs.

Furthermore, there is an ink jet recording apparatus which is providedwith an ink storage container in which the atmosphere and the ink can bein contact with each other, like the open type ink cartridge. Even whenthe ink is supplied to the print head in the ink jet recordingapparatus, ink including bubbles is carried to the print head, and aproblem of a filling failure or a discharging failure in the print headoccurs. The filling failure and the discharging failure in the printhead cause a deterioration of initial filling characteristics andcontinuous printing stability.

Here, a first advantage of the present invention is to provide an inkcomposition for ink jet recording having excellent initial fillingcharacteristics and continuous printing stability even in a case of anink composition (for example, dissolved nitrogen is equal to or greaterthan 5 ppm) which is almost not deaerated or an ink composition (forexample, dissolved nitrogen is equal to or greater than 7 ppm) which iscompletely deaerated.

Here, a second advantage of the present invention is to provide an inksupply system and an ink jet recording apparatus, in which at least anyone of the initial filling characteristics and the continuous printingstability is excellent, even in a case of the ink which is stored in theink storage container that can bring the atmosphere and the ink intocontact with each other and which includes bubbles.

Therefore, the advantages of the present invention are to achieve atleast one of the above-described first or second advantages.

Solution to Problem

The inventors have thoroughly investigated the solutions to theabove-described problems. As a result, the inventors found that theabove-described problem is solved by an ink composition for ink jetrecording including an alkylene oxide adduct of acetylenic glycol inwhich a main chain has 12 or more carbon atoms, acetylenic glycol inwhich the main chain has 10 or more carbon atoms, and polyoxyalkylenealkyl ether, and completed a first present invention (embodiment A).

In addition, the inventors found that the above-described problem issolved by an ink supply system which is provided with a filter in an inksupply path that connects the ink storage container and a print head toeach other, and which makes the ink composition supplied (including“replenishing”, and the same applies to the following) from the inkstorage container to the print head have a predetermined compositioneven when the ink storage container in which the atmosphere and the inkcan be brought into contact with each other is used, and completed asecond present invention (embodiment B).

In other words, preferable aspects of the present invention are asfollows.

[1]

An ink composition for ink jet recording, including: an alkylene oxideadduct (A) of acetylenic glycol in which a main chain has 12 or morecarbon atoms; acetylenic glycol (B) in which the main chain has 10 ormore carbon atoms; and polyoxyalkylene alkyl ether (C).

[2]

The ink composition for ink jet recording described in [1], in which anHLB value of the polyoxyalkylene alkyl ether (C) is 12 to 16.

[3]

The ink composition for ink jet recording described in [1], in which thealkylene oxide adduct is an ethylene oxide adduct.

[4]

The ink composition for ink jet recording described in [1], in which amass ratio between a content of polyoxyalkylene alkyl ether (C) and atotal content of alkylene oxide adduct (A) of acetylenic glycol in whichthe main chain has 12 or more carbon atoms and acetylenic glycol (B) inwhich the main chain has 10 or more carbon atoms is 0.10:1.0 to0.50:1.0.

[5]

The ink composition for ink jet recording described in [1], in which anHLB value of the alkylene oxide adduct (A) of acetylenic glycol in whichthe main chain has 12 or more carbon atoms is 8 to 15.

[6]

The ink composition for ink jet recording described in [1], in which anHLB value of the acetylenic glycol (B) in which the main chain has 10 ormore carbon atoms is equal to or less than 4.

[7]

The ink composition for ink jet recording described in [1], furtherincludes a coloring agent.

[8]

The ink composition for ink jet recording described in [1], furtherincludes an organic solvent.

[9]

An ink supply system, including: an ink storage container in which theatmosphere and the ink can be brought into contact with each other andwhich stores the ink described in [1]; a print head which discharges theink; an ink supply path which connects the ink storage container and theprint head to each other, and in which the ink flows to the print headfrom the ink storage container; and a filter (D) which is provided inthe ink supply path.

[10]

The ink supply system described in [9], in which an average porediameter of the filter is equal to or less than a nozzle diameter of anozzle of the print head.

[11]

The ink supply system described in [9], in which a plurality of filters(D) are provided in the ink supply path.

[12]

The ink supply system described in [9], in which a material of thefilter (D) is a resin.

[13]

An ink jet recording apparatus, including the ink supply systemdescribed in [9], in which the ink supplied to the print head from theink storage container is discharged toward a recording medium from theprint head and a recording is performed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating the entire configuration of aprinter which is provided with an ink supply system.

FIG. 2 is a schematic view illustrating a horizontal cross-section ofthe printer which is provided with the ink supply system.

FIG. 3 is a schematic view for describing a principle of ink supply to ahead from an ink tank which is an example of an ink storage container.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments for realizing the present invention will bedescribed in detail, preferably for each embodiment A and embodiment B.In addition, the present invention is not limited to the embodimentsdescribed below, and various modifications within the scope of theinvention can be realized.

Embodiment A Ink Composition for Ink Jet Recording

An embodiment of the present invention relates to an ink composition(hereinafter, simply referred to as an “ink composition”) for ink jetrecording. The ink composition includes: an alkylene oxide adduct (A) ofacetylenic glycol in which a main chain has 12 or more carbon atoms;acetylenic glycol (B) in which the main chain has 10 or more carbonatoms; and polyoxyalkylene alkyl ether (C).

Hereinafter, additives (components) which are included or can beincluded in the ink composition of the embodiment A will be described.

Alkylene Oxide Adduct (A) of Acetylenic Glycol in which Main Chain has12 or More Carbon Atoms

The ink composition of the embodiment A includes the alkylene oxideadduct (A) (hereinafter, the alkylene oxide adduct is referred to as an“AO adduct”) of acetylenic glycol in which the main chain has 12 or morecarbon atoms. The AO adduct of acetylenic glycol in which the main chainhas 12 or more carbon atoms includes acetylenic glycol-based surfactanttogether with acetylenic glycol in which the main chain has 10 or morecarbon atoms that will be described later. In addition, the “main chain”in the specification means a main chain which is based on IUPACnomenclature.

The above-described acetylenic glycol-based surfactant is included in anonionic surfactant. The nonionic surfactant operates to uniformlyspread ink on a recording medium. For this reason, when the ink jetrecording is performed by using the ink composition including thenonionic surfactant, it is possible to obtain an image having little inkbleeding and a relatively high definition.

Among the acetylenic glycol-based surfactants, a surfactant in which themain chain has 12 or more carbon atoms has an excellent wettability withrespect to foreign substances that can be a reason for occurrence ofbubbles in polymer members, such as rubber or plastic, that constitutesthe ink flow path, and the ink. Accordingly, it is possible to suppressretention of the generated bubbles on a flow path surface of the polymermember from an ink tank to a head. Accordingly, initial fillingcharacteristics are excellent, and dot omission due to a growth of theretained bubbles and detachment of the bubbles attached to the flow pathsurface, can also be prevented. As a result, continuous printingstability becomes excellent.

There is a case where acetylenic glycol in which the main chain has 12or more carbon atoms cannot be dissolved (dispersed) stably inwater-based ink including water as a solvent. In contrast, the AO adductof acetylenic glycol in which the main chain has 12 or more carbon atomshas an excellent solubility in the above-described water-based ink.

In addition, the above-described matter is a matter which merelydescribes a case where the ink composition of the embodiment A includesacetylenic glycol in which the main chain has 12 or more carbon atomsinstead of the AO adduct of acetylenic glycol in which the main chainhas 12 or more carbon atoms, and is an item which is totally unrelatedto acetylenic glycol in which the main chain has 12 or more carbon atomsamong acetylenic glycols in which the main chain has 10 or more carbonatoms (to be described later). In other words, when the ink compositionof the embodiment A includes the AO adduct of acetylenic glycol in whichthe main chain has 12 or more carbon atoms and acetylenic glycol inwhich the main chain has 12 or more carbon atoms among acetylenicglycols in which the main chain has 10 or more carbon atoms, thesolubility is excellent in the water-based ink.

It is preferable that an HLB (hydrophile-lipophile balance) value of theAO adduct of acetylenic glycol in which the main chain has 12 or morecarbon atoms be 8 to 15 since the above-described wettability issuperior. In addition, the HLB value in the specification is an HLBvalue which is defined by a Griffin method.

Examples of the AO adduct of acetylenic glycol in which the main chainhas 12 or more carbon atoms are not limited to the description below,but can include ethoxylates of acetylenic glycol which is represented bythe general formula (1) described below.

R¹, R^(1′), R², and R^(2′) in the above-described formula (1) areindependent of each other and represent an alkyl group which has 1 to 5carbon atoms, and have a main chain which has 12 or more carbon atoms.—OR³ represents —OH or —O(C₂H₄O)_(m)H. —OR^(3′) represents —OH or—O(C₂H₄O)_(m)—H. At this time, m and n are independent of each other,and are values which include a decimal from 0.5 to 25. m+n is a valuewhich includes a decimal from 1 to 40 (However, a case where both —OR³and —OR^(3′) are —OH is excluded).

Specific examples of the AO adduct of acetylenic glycol in which themain chain has 12 or more carbon atoms are not limited to thosedescribed below, but can preferably include ethoxylates of2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, and ethoxylates of5,8-dimethyl-6-dodecyne-5,8-diol.

An ethylene oxide adduct of acetylenic glycol and a propylene oxideadduct of acetylenic glycol are preferable among the above-describedalkylene oxide adducts of acetylenic glycol. The ethylene oxide adductof acetylenic glycol is more preferable. It is preferable that, in eachof R3 and R3′, the number of additional moles of a unit of an ethyleneoxide in acetylenic glycol be 1 to 20 moles, respectively, and that thetotal number of the additional moles (sum of R3 and R3′) be 2 to 40moles. When the total number of the additional moles of the ethyleneoxide is equal to or less than 40 moles, it is possible to reduce astatic and a dynamic surface tension, and an absorption performance ofthe ink becomes excellent.

Examples of a commercial product of the AO adduct of acetylenic glycolin which the main chain has 12 or more carbon atoms are not limited tothe description below, but can include Olefin EXP 4300 (name of productmanufactured by Nissin Chemical Industry Co., Ltd, 12 carbon atoms,ethylene oxide adduct).

One type of AO adduct of acetylenic glycol in which the main chain has12 or more carbon atoms may be used independently, and two or more typesof AO adducts of acetylenic glycol in which the main chain has 12 ormore carbon atoms may be used.

It is preferable to consider the sum with the content of acetylenicglycol in which the main chain has 10 or more carbon atoms describedbelow for the content of the AO adduct of acetylenic glycol in which themain chain has 12 or more carbon atoms. Then, the content of the AOadduct of acetylenic glycol in which the main chain has 12 or morecarbon atoms may be 0.05 mass % to 0.30 mass %, for example, withrespect to the total mass (100 mass %) of the ink composition.

Acetylenic Glycol (B) in which Main Chain has 10 or More Carbon Atoms

The ink composition of the embodiment A includes acetylenic glycol inwhich the main chain has 10 or more carbon atoms. Among the acetylenicglycol-based surfactants, acetylenic glycol in which the main chain has10 or more carbon atoms can effectively eliminate bubbles generated inthe ink. Accordingly, the initial filling characteristics and thecontinuous printing stability become excellent.

Since the defoaming properties are excellent, the HLB value ofacetylenic glycol in which the main chain has 10 or more carbon atoms ispreferably equal to or less than 7, and more preferably, 3 to 5.

In addition, in a case of acetylenic glycol in which the main chain has10 or more carbon atoms, if an alkylene oxide is not added, thedefoaming properties are excellent. Acetylenic glycol in which the mainchain has 10 or more carbon atoms has excellent defoaming propertiessince acetylenic glycol is a component which is difficult to bedissolved in water.

Examples of acetylenic glycol in which the main chain has 10 or morecarbon atoms are not limited to the description below, but can includeacetylenic glycol which is represented by the general formula (2)described below.

R¹, R^(1′), R², and R^(2′) in the above-described formula (2) areindependent of each other and represent an alkyl group which has 1 to 5carbon atoms, and has a main chain which has 10 or more carbon atoms. Inaddition, R¹, R^(1′), R², and R^(2′) in the formula (2) are not relatedto R¹, R^(1′), R², and R^(2′) in the above-described formula (1).

Specific examples of acetylenic glycol in which the main chain has 10 ormore carbon atoms are not limited to those described below, but canpreferably include 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol,5,8-dimethyl-6-dodecyne-5,8-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol,and 4,7-dimethyl-5-decyne-4,7-diol.

Examples of a commercial product of acetylenic glycol in which the mainchain has 10 or more carbon atoms are not limited to those describedbelow, but can include Surfynol 104PG50(2,4,7,9-tetramethyl-5-decyne-4,7-diol) and Surfynol DF110D(2,5,8,11-tetramethyl-6-dodecyne-5,8-diol) (those described above arenames of products manufactured by Air Products and Chemicals, Inc.)

One type of acetylenic glycol in which the main chain has 10 or morecarbon atoms may be used independently, and two or more types ofacetylenic glycol in which the main chain has 10 or more carbon atomsmay be used in combination.

It is preferable to consider the sum with the content of theabove-described AO adduct of acetylenic glycol in which the main chainhas 12 or more carbon atoms for the content of acetylenic glycol inwhich the main chain has 10 or more carbon atoms. Then, the content ofacetylenic glycol in which the main chain has 10 or more carbon atomsmay be 0.05 mass % to 0.30 mass %, for example, with respect to thetotal mass (100 mass %) of the ink composition.

The total content of acetylenic glycol in which the main chain has 10 ormore carbon atoms and the AO adduct of acetylenic glycol in which themain chain has 12 or more carbon atoms is preferably 0.1 mass % to 0.6mass %, and more preferably, 0.1 mass % to 0.5 mass %. When the totalcontent is within this range, the solubility in water becomes excellent,and it is possible to effectively prevent occurrence of aggregates whenthese acetylenic glycols are combined.

In addition, the mass ratio between the content of acetylenic glycol inwhich the main chain has 10 or more carbon atoms and the above-describedAO adduct of acetylenic glycol in which the main chain has 12 or morecarbon atoms is preferably 0.5:1 to 2.5:1, more preferably, 0.5:1 to2.0:1, and still more preferably, 0.5:1 to 1.5:1. When the mass ratio iswithin this range, it is possible to make the ink composition for inkjet recording which has excellent initial filling characteristics andcontinuous printing stability.

Polyoxyalkylene Alkyl Ether (C)

The ink composition of the embodiment A includes polyoxyalkylene alkylether. Both the above-described AO adducts of acetylenic glycol in whichthe main chain has 12 or more carbon atoms and acetylenic glycol inwhich the main chain has 10 or more carbon atoms do not have excellentsolubility in water or a water-based organic solvent. Here, when the inkcomposition further includes polyoxyalkylene alkyl ether, thepolyoxyalkylene alkyl ether acts as a solubilizing agent which dissolvesor disperses the above-described acetylenic glycol into the ink. Inother words, the polyoxyalkylene alkyl ether is a solubilizing agent forthe above-described acetylenic glycol-based compound. Furthermore, anyof the above-described acetylenic glycols has a low dynamic surfacetension, and the polyoxyalkylene alkyl ether can be a solubilizing agentwhich does not influence the low dynamic surface tension.

Since the initial filling characteristics and the continuous printingstability are superior, the HLB value of polyoxyalkylene alkyl ether ispreferably 11 to 16, and more preferably, 12 to 15.

Examples of polyoxyalkylene alkyl ether are not limited to thosedescribed below, but can include a compound represented by the formula(3) described below.

R⁴O(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H  (3)

In the above-described formula (3), R⁴ represents an alkyl group whichhas 1 to 20 carbon atoms, w is in a range of 1 to 20, and x, y, and zare independent of each other and are 0 or in a range of 1 to 20.However, w+x+y+z=5 to 30.

In the above-described formula (3), R⁴ is preferably an alkyl groupwhich has 5 to 15 carbon atoms, and more preferably, an alkyl groupwhich has 10 to 15 carbon atoms. In addition, w+x+y+z is preferably 5 to30, and more preferably, 5 to 25.

Specific examples of polyoxyalkylene alkyl ether include the chemicalformulas below. In addition, polyoxyalkylene alkyl ether is not limitedto those described below.

C₁₂H₂₅O(C₂H₄O)₆(C₃H₆O)₂(C₂H₄O)₆(C₃H₆O)₈H,

C₁₃H₂₇O(C₂H₄O)₆(C₃H₆O)₂(C₂H₄O)₆(C₃H₆O)₈H,

C₁₂H₂₅O(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H

(wherein w+y=15, and x+z=4),

C₁₃H₂₇O(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H

(wherein w+y=15, and x+z=4),

C₁₂H₂₅O(C₂H₄O)₈(C₃H₆O)₂(C₂H₄O)₆H,

C₁₃H₂₇O(C₂H₄O)₈(C₃H₆O)₂(C₂H₄O)₆H,

C₁₂H₂₅O(C₂H₄O)₁₂(C₃H₆O)₂(C₂H₄O)₁₂H,

C₁₃H₂₇O(C₂H₄O)₁₂(C₃H₆O)₂(C₂H₄O)₁₂H,

CH₃(CH₂)₉(CH₃)CHO(C₂H₄O)₇(C₃H₆O)_(4.5)H,

CH₃(CH₂)₂₂(CH₃)CHO(C₂H₄O)₇(C₃H₆O)_(4.5)H_(r)

CH₃(CH₂)₉(CH₃)CHO(C₂H₄O)₅(C₃H₆O)_(3.5)H_(r)

CH₃(CH₂)₁₁(CH₃)CHO(C₂H₄O)₅(C₃H₆O)_(3.5)H_(r)

C₁₄H₂₉O(C₂H₄O)₁₄(C₃H₆O)₂H,

C₁₁H₂₃O(C₂H₄O)₈H,

C₁₀H₂₁O(C₂H₄O)₂₂H, and

C₁₂H₂₅O(C₂H₄O)₁₅H are included in the examples.

Examples of a commercial product of polyoxyalkylene alkyl ether are notlimited to those described below, but can include Noigen DL-0415(RO(C₂H₄O)_(w)(C₂H₆O)_(x)(C₂H₄O)_(y)(C₂H₆O)_(z)H, “R”: alkyl which has12 or 13 carbon atoms, w+y=15, x+z=4, HLB value is 15.0), Noigen ET-116B(RO(C₂H₄O)_(w)(C₂H₆O)_(x)H, “R”: alkyl which has 12 or 14 carbon atoms,w=7, x=4.5, HLB value is 12.0), Noigen ET-106A(RO(C₂H₄O)_(w)(C₂H₆O)_(x)H, “R”: alkyl which has 12 or 14 carbon atoms,w=5, x=3.5, HLB value is 10.9), Noigen DH-0300 (RO(C₂H₄O)_(w)H, “R”:alkyl which has 14 carbon atoms, w=2, HLB value is 4.0), Noigen YX-400(RO(C₂H₄O)_(w)H, “R”: alkyl which has 12 carbon atoms, w=40, HLB valueis 18.1), Noigen EA-160 (C₉H₁₉C₆H₄O(C₂H₄O)_(w)H, w=16.8, HLB value is15.4), (those described above are names of products manufactured byDai-ichi Kogyo Seiyaku Co., Ltd.), and Emulgen 1108 (name of productmanufactured by Kao Corporation, RO(C₂H₄O)_(w)H, “R”: alkyl which has 11carbon atoms, w=8, HLB value is 13.4).

One type of polyoxyalkylene alkyl ether may be used independently, andtwo or more types of polyoxyalkylene alkyl ether may be used. Thecontent of polyoxyalkylene alkyl ether is not particularly limited, butmay be 0.01 mass % to 0.50 mass %, for example, with respect to thetotal mass (100 mass %) of the ink composition.

In addition, it is preferable to consider the content of the AO adductof acetylenic glycol in which the main chain has 12 or more carbon atomsfor the content of polyoxyalkylene alkyl ether. The mass ratio (theformer:the latter) between the content of polyoxyalkylene alkyl ether(the former) and the content of the AO adduct of acetylenic glycol inwhich the main chain has 12 or more carbon atoms (the latter) ispreferably 0.10:1.0 to 1.0:1.0, and more preferably, 0.30:1.0 to0.70:1.0. When the mass ratio is within this range, the AO adduct ofacetylenic glycol in which the main chain has 12 or more carbon atoms issufficiently solubilized, and it is possible to effectively preventgeneration of aggregates at a time of combination and occurrence ofirregularity in absorbability of the ink since the solubility isexcellent.

In addition, it is preferable to consider the total content of the AOadduct of acetylenic glycol in which the main chain has 12 or morecarbon atoms and acetylenic glycol in which the main chain has 10 ormore carbon atoms for the content of polyoxyalkylene alkyl ether. Themass ratio (the former:the latter) between the content ofpolyoxyalkylene alkyl ether (the former) and the total content of the AOadduct of acetylenic glycol in which the main chain has 12 or morecarbon atoms and acetylenic glycol in which the main chain has 10 ormore carbon atoms (the latter) is preferably 0.10:1.0 to 0.5:1.0, andmore preferably, 0.10:1.0 to 0.40:1.0. When the mass ratio is withinthis range, the acetylenic glycol-based compound is sufficientlysolubilized and the solubility is excellent. Therefore, it is possibleto effectively prevent the generation of aggregates at a time ofcombining polyoxyalkylene alkyl ether and acetylenic glycol-basedcompound, and the occurrence of irregularity in absorbability of theink.

[Surfactant Other than Those Described Above]

The ink in the embodiment A may include a surfactant (hereinafter,referred to as “the other surfactant”) other than those described above.

Coloring Agent

It is preferable that the ink in the embodiment A further include acoloring agent. Examples of the coloring agent are not particularlylimited, and any of a dye and a pigment can be used. Examples of colorswhich are provided by the coloring agent include yellow, magenta, cyan,black, white, green, orange, red, blue, light yellow, light magenta,light yellow, light black, light green, light orange, light red, andlight blue.

As the pigment, it is possible to use at least any one of an inorganicpigment and an organic pigment. Among these, examples of the inorganicpigment are not limited to those described below, but can include atitanium oxide, an iron oxide, calcium carbonate, barium sulfate,aluminium hydroxide, barium yellow, cadmium red, chrome yellow, carbonblack, dark blue, and metal powders.

Examples of the above-described organic pigment are not limited to thosedescribed below, but can include an azo pigment, a polycyclic pigment, anitro pigment, a nitroso pigment, and aniline black. Among the examples,at least any one of the azo pigment and the polycyclic pigment ispreferable. Among these, examples of the azo pigment are not limited tothose described below, but can include an azo lake pigment, an insolubleazo pigment, a condensed azo pigment, and a chelate azo pigment.Examples of the polycyclic pigment are not limited to those describedbelow, but can include a phthalocyanine pigment, a perylene pigment, aperionone pigment, an anthraquinone pigment, a quinacridone pigment, adioxazine pigment, an indigo pigment, a thioindigo pigment, anisoindolinone pigment, a quinophthalone pigment, an azomethine-basedpigment, and a rhodamine B lake pigment.

A dispersion state of the pigment in a case where a pigment is used asthe coloring agent is not particularly limited, but it is preferablethat at least one of pigments among a pigment on which a surfacetreatment has been performed and a pigment which uses a dispersant beused. The above-described pigment on which a surface treatment has beenperformed is a pigment which directly or indirectly bonds and makes ahydrophilic group (carboxyl group, sulfonate group, or the like) on apigment surface dispersible in an aqueous solvent by a physicaltreatment or a chemical treatment (hereinafter, referred to as a “selfdispersion type pigment”). The pigment which uses the dispersant is apigment which is dispersed by a surfactant or a resin (hereinafter,referred to as a “polymer dispersion type pigment). A known substancecan be used for both of the surfactant and the resin. In addition, the“polymer dispersion type pigment” can also include a pigment which iscoated with the resin. The pigment which is coated with the resin can beobtained by an acid deposition method, a phase inversion emulsificationmethod, and a mini-emulsion polymerization method.

In addition, as the dye, it is possible to use an oil-soluble dye or awater-soluble dye. Among these, examples of the oil-soluble dye are notlimited to those described below, but can include a pigment which isclassified as a disperse dye in a color index. Examples of thewater-soluble dye are not limited to those described below, but caninclude each of dyes which are classified as an acid dye, a direct dye,a basic dye, a reactive dye, and an edible dye.

Examples of the above-described acid dye and edible dye are not limitedto those described below, but can include: C. I. acid yellow 17, 23, 42,44, 79, 142; C. I. acid red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52,82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289; C. I.acid blue 9, 29, 45, 92, 249; C. I. acid black 1, 2, 7, 24, 26, 94; C.I. food yellow 3, 4; C. I. food red 7, 9, 14; and C. I. food black 1, 2.

Examples of the direct dye are not limited to those described below, butcan include: C. I. direct yellow 1, 12, 24, 26, 33, 44, 50, 86, 120,132, 142, 144; C. I. direct red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81,83, 89, 225, 227; C. I. direct orange 26, 29, 62, 102; C. I. direct blue1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202; andC. I. direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168,171.

Examples of the basic dye are not limited to those described below, butcan include: C. I. basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24,25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77,87, 91; C. I. basic red, 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35,36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70, 73, 78, 82, 102, 104,109, 112; C. I. basic blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47,54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93, 105, 117, 120, 122, 124,129, 137, 141, 147, 155; and C. I. basic black 2, 8.

Examples of the reactive dye are not limited to those described below,but can include: C. I. reactive black 3, 4, 7, 11, 12, 17; C. I.reactive yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65,67; C. I. reactive red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66,74, 79, 96, 97; and C. I. reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38,41, 63, 80, 95.

The content of the coloring agent is not particularly limited, and canbe appropriately selected depending on a purpose. However, sincechromogenic characteristics are excellent, the content of the coloringagent is preferably 2 mass % to 10 mass % with respect to the total mass(100 mass %) of the ink composition.

In addition, the ink composition of the embodiment A may be transparentclear ink which does not substantially include a coloring agent.

Water

The ink in the embodiment A may contain water. In particular, when theink is aqueous ink, the water is a main solvent of the ink composition,and when the recording medium is heated in the ink jet recording, thewater is a component which evaporates and is distributed.

Examples of water include pure water, such as ion exchanged water,ultrafiltration water, Milli Q water, or distilled water, and water inwhich ionic impurities are eliminated as much as possible, such ashyperpure water. In addition, when water which is sterilized byultraviolet irradiation or addition of hydrogen peroxide is used, it ispossible to prevent mold or bacteria from being generated when pigmentdispersions and ink which use the same are stored for a long time.

The content of water is not particularly limited, but can beappropriately selected as necessary.

In addition, the ink which contains the water or the water-based organicsolvent as the main solvent corresponds to the aqueous ink. Here, the“main solvent” refers to as a solvent component which has the highestcontent among all of the solvents in the ink composition. In addition,the “water-based organic solvent” in the specification means a mixedsolvent of water and a water-soluble organic solvent.

Organic Solvent

It is preferable that the ink in the embodiment A further include anorganic solvent. Among organic solvents, a volatile water-solubleorganic solvent is preferable. Examples of the volatile water-solubleorganic solvent are not limited to those described below, but caninclude an alcohol type solvent, such as glycerin, ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol, dipropyleneglycol, 1,3-propanediol, 1,2-butanediol, 1,2-pentanediol,1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propylether, diethylene glycol mono-iso-propyl ether, ethylene glycolmono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethyleneglycol mono-n-butyl ether, triethylene glycol monobutyl ether,diethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether,propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether,propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propylether, propylene glycol mono-n-butyl ether, dipropylene glycolmono-n-butyl ether, dipropylene glycol mono-n-propyl ether, dipropyleneglycol mono-iso-propyl ether, diethylene glycol dimethyl ether,diethylene glycol diethyl ether, diethylene glycol dibutyl ether,diethylene glycol ethyl methyl ether, diethylene glycol butyl methylether, triethylene glycol dimethyl ether, tetraethylene glycol dimethylether, dipropylene glycol dimethyl ether, dipropylene glycol diethylether, tripropylene glycol dimethyl ether, methanol, ethanol, n-propylalcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol,iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, or tert-pentanol, or aglycol type solvent, N,N-dimethylformamide, N,N-dimethylacetamide,2-pyrrolidone, N-methyl-2-pyrrolidone, 2-oxazolidone,1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, sulfolane, and1,1,3,3-tetramethylurea.

One type of organic solvent may be used independently, and a combinationof two or more types of organic solvent may be used. The content of theorganic solvent is not particularly limited, and can be appropriatelyselected as necessary. For example, when the ink has an excellentpenetrability into the recording medium, it is preferable to use one ormore types of solvent which are selected from a group consisting of1,2-hexanediol, triethylene glycol monobutyl ether, and dipropyleneglycol monopropyl ether.

In addition, the sum content of the water and the organic solvent may be60 mass % to 98 mass % with respect to the total mass (100 mass %) ofthe ink composition.

Other Components

In addition to the above-described materials, the ink composition of theembodiment A may include a pH adjuster, such as triethanolamine ortripropanolamine, a preservative and a fungicide, a rust preventive, ora chelating agent.

Method of Manufacturing Ink Composition

The ink composition of the embodiment A can be obtained by mixing theabove-described materials (components) in an arbitrary order, performingfiltration if necessary, and eliminating impurities. Here, at a time ofmixing the AO adduct of acetylenic glycol in which the main chain has 12or more carbon atoms, acetylenic glycol in which the main chain has 10or more carbon atoms, and the above-described polyoxyalkylene alkylether, it is preferable that the temperature be 10° C. to 30° C.

In addition, it is preferable to mix in the pigment after adjusting to astate where the pigment is uniformly dispersed in the solvent inadvance, since this is easy to handle.

As a method for mixing in each material, a method of mixing in by addingthe materials in order into a container provided with a stirringapparatus, such as a mechanical stirrer or a magnetic stirrer, andstirring, is appropriately used. As a method of filtering, for example,it is possible to perform centrifugal filtration, filtration by using afilter, or the like, if necessary.

In this manner, according to the embodiment A, even in a case of an inkcomposition which is almost not deaerated (for example, dissolvednitrogen is equal to or greater than 5 ppm) and an ink composition whichis not deaerated (for example, dissolved nitrogen is equal to or greaterthan 7 ppm) at all, it is possible to provide an ink composition whichhas excellent initial filling characteristics and continuous printingstability, and furthermore, which even has excellent dissolutionstability and preservation stability. In other words, even without beingdeaerated, it is possible to provide an ink composition which cansuppress the discharging failure and which has excellent initial fillingcharacteristics and continuous printing stability. In other words, forexample, even when bubbles are generated in the ink, it is possible toprovide an ink composition in which the bubbles are easily eliminated.

Ink Jet Recording Method

The ink jet recording method according to one embodiment A of thepresent invention performs recording on a recording surface of arecording medium using the ink composition of the above-describedembodiment A, and obtains a recorded matter.

Hereinafter, the recording medium which is used in the ink jet recordingmethod (hereinafter, referred to as a “recording method”) of theembodiment A will be described, and then, an example of the recordingmethod will be described.

Recording Medium

Examples of the recording medium are not particularly limited, but caninclude a recording medium with ink absorbing properties. Examples ofthe recording medium with absorbing properties are not particularlylimited, but can include a plain paper sheet, such as anelectrophotographic paper sheet having a high penetrability of theaqueous ink, an ink jet paper sheet (an ink jet dedicated paper sheetwhich is provided with an ink absorbing layer made of silica particlesor alumina particles, or an ink absorbing layer made of a hydrophilicpolymer, such as polyvinyl alcohol(PVA) or polyvinylpyrrolidone(PVP)),an art paper sheet which is used in general offset printing havingrelatively low penetrability of the aqueous ink, a coated paper sheet,or a cast paper sheet.

Discharging Process

The ink jet recording method of the embodiment A includes a dischargingprocess. In the discharging process, by the ink jet recording method,ink droplets of the ink composition are discharged onto the recordingmedium, and an image is formed. As a discharging method, known methodsin the related art can be used. Among these methods, when a method (arecording method which uses a head that forms the ink droplets bymechanically deforming an electrostrictive element) of discharging thedroplets by using vibration of a piezoelectric element is used, anexcellent recording can be performed.

Embodiment B Ink Supply System

One embodiment of the present invention relates to an ink supply system.The ink supply system includes: an ink storage container in which theatmosphere and the ink can be brought into contact with each other andwhich stores the ink; a print head which discharges the ink; an inksupply path which connects the ink storage container and the print headwith each other and in which the ink flows to the print head from theink storage container; and a filter (D) which is provided in the inksupply path. The ink contains an alkylene oxide adduct (A) (hereinafter,the alkylene oxide adduct is referred to as an “AO adduct”) ofacetylenic glycol in which a main chain has 12 or more carbon atoms andpolyoxyalkylene alkyl ether (C).

The ink supply system of the embodiment B eliminates bubbles during thetime when the ink including bubbles stored in the ink storage containerreaches the print head (hereinafter, simply referred to as a “head”)through the ink supply path. In particular, the AO adduct of acetylenicglycol in which the main chain has 12 or more carbon atoms gives the inkan excellent wettability, and incorporates the bubbles attached tomembers, such as the ink storage container or the ink supply path, intothe ink. In addition, when the ink into which the bubbles areincorporated passes through the filter (D), the filter (D) captures thebubbles incorporated into the ink and eliminates the bubbles from theink.

Ink Jet Recording Apparatus

One embodiment of the present invention relates to an ink jet recordingapparatus (hereinafter, simply referred to as a “recording apparatus” ora “printer”). The ink supply system of the embodiment B can be executedby using the recording apparatus. In particular, the recording apparatusis provided with the above-described ink supply system, and performs therecording by discharging the ink supplied to the print head from the inkstorage container, toward the recording medium from the print head.Therefore, hereinafter, the recording apparatus of the embodiment B isdescribed in detail, and the ink supply system of the embodiment B willbe described in detail.

The recording apparatus provided with the above-described ink supplysystem can be classified into several types according to a method of therecording apparatus and a supplying method of the ink. Examples of atype classified by the method of the recording apparatus can include aline printer and a serial printer. In short, the line printer is aprinter which is provided with a line head having a length thatcorresponds to a width of the recording medium, in which the head isfixed (almost) without moving, and which performs printing by one pass(single pass). Meanwhile, the serial printer is a printer which performsprinting generally by two or more passes (multi pass) while the headperforms a reciprocating movement (shuttle movement) in a directionperpendicular to a transporting direction of the recording medium. Inaddition, examples of a type classified by the supplying method of theink can include an on-carriage type serial printer and an off-carriagetype serial printer. The on-carriage type serial printer, theoff-carriage type serial printer, and the line printer will be describedlater.

Hereinafter, the ink supply system and the recording apparatus providedwith the same will be described by using the off-carriage type serialprinter as an example among the types above with reference to thedrawings. Here, the off-carriage type serial printer is a printer whichconnects the ink storage container, such as an ink tank or an inkcartridge, and a head of the carriage with an ink supply path, such as atube.

In addition, in each drawing used in the description below, in order tomake each constituent element (members) have a recognizable size, thedimensions for every constituent element are appropriately modified. Theembodiment B is not limited only to the number, shape, and size ratio ofthe constituent elements, and the relative positional relationship ofeach constituent element, which are illustrated in the drawings.

1. Configuration of Recording Apparatus

FIG. 1 is a block diagram illustrating a configuration of a printer 1which is provided with the ink supply system. FIG. 2 is a schematic viewillustrating a horizontal cross-section of the printer 1 which isprovided with the ink supply system.

The printer 1 of the embodiment B is an apparatus which forms an imageon a recording surface of a recording medium by discharging ink toward arecording medium, such as a paper sheet. Here, the printer 1 of theembodiment B can form an image by using various colors of ink. Forexample, the image is formed by using 4 colors of ink, such as cyan,magenta, yellow, and black (hereinafter, each color is referred to as“C”, “M”, “Y”, and “Bk”), or a base which gives excellent concealingproperties to the recording medium by using white ink is formed.Furthermore, clear ink can be coated onto the CMYBk ink or the whiteink, and accordingly, it is possible to improve glossiness.

The printer 1 includes a transport unit 10, a carriage unit 20, a headunit 30, an ink storage unit 40, a detector group 50, and a controller60. The printer 1 which receives printing data from a computer 110 whichis an external apparatus controls each unit (transport unit 10, carriageunit 20, head unit 30, ink storage unit 40) by the controller 60. Thecontroller 60 controls each unit and prints the image on the recordingmedium, based on the printing data received from the computer 110. Asituation in the printer 1 is monitored by the detector group 50, andthe detector group 50 outputs a detection result to the controller 60.The controller 60 controls each unit based on the detection resultoutput from the detector group 50.

The transport unit 10 is a unit for transporting the recording medium,such as the paper sheet, in a predetermined direction (hereinafter,referred to as a “transport direction” or a “sub-scanning direction”).The transport unit 10 includes a paper supply roller 11, a transportmotor (not illustrated), a transport roller 13, a platen 14, and a paperejection roller 15. The paper supply roller 11 is a roller for supplyingthe recording medium which is inserted into a paper insertion port, intothe printer 1. The transport roller 13 is a roller for transporting therecording medium supplied by the paper supply roller 11 to an area whereprinting is possible, and is operated by the transport motor. The platen14 supports the recording medium during printing. The paper ejectionroller 15 is a roller for ejecting the recording medium to the outsideof the printer 1, and is provided on a downstream side in thetransporting direction with respect to the area where printing ispossible.

The carriage unit 20 is a movement mechanism which moves, that is, scansa head 31 in a direction (hereinafter, referred to as a “movementdirection” or a “main scanning direction”) which intersects with theabove-described transporting direction (sub-scanning direction) whiledischarging the ink, with respect to the recording medium which is madestationary in a recording area. The carriage unit 20 includes a carriage21, a carriage motor (not illustrated), and a sub-tank (sub-ink tank)22. The carriage 21 includes the sub-tank 22 and the head 31, and isconnected to the carriage motor (not illustrated) via a timing belt (notillustrated). The carriage 21 performs the reciprocating movement alonga guide shaft 24 through the carriage motor in a state of beingsupported by the guide shaft 24 which intersects with the transportingdirection (to be described later). The guide shaft 24 is supported sothat the carriage 21 can perform the reciprocating movement in a shaftline direction of the guide shaft 24. The sub-tank 22 is for suppressinga pressure change of the ink inside the head 31, which can be generatedby the reciprocating movement of the carriage 21.

Although not illustrated in the drawings, the sub-tank 22 has foursub-tanks, for example, and may store different colors of ink,respectively. Specific examples of the four sub-tanks 22 can include asub-tank which stores black ink, a sub-tank which stores cyan ink, asub-tank which stores magenta ink, and a sub-tank which stores yellowink. Any of the four sub-tanks 22 can be mounted on the carriage 21.

In addition, the carriage unit 20 may not be provided with the sub-tank22. In this case, an ink storage container 41 and the head 31 areconnected to each other via an ink supply path 42. The sub-tank 22 willbe described in more detail in FIG. 3 which will be described later.

The head unit 30 is for discharging the ink onto the recording medium.The head unit 30 is provided with the head 31 having a plurality ofnozzles. Since the head 31 is provided in the carriage 21, when thecarriage 21 moves in the movement direction, the head 31 also moves inthe movement direction. As the ink is discharged while the head 31 movesin the movement direction, an image is formed on the recording surfaceof the recording medium.

Although not illustrated in the drawings, for example, four heads 31 maydischarge the inks which correspond to the colors stored in theabove-described four sub-tanks 22. In other words, specific examples ofthe four heads 31 can include each head 31 for discharging each of theblack ink, the cyan ink, the magenta ink, and the yellow ink.

The ink storage unit 40 stores the ink and supplies the stored ink tothe head 31 via the ink supply path. The ink storage unit 40 includesthe ink storage container 41, the ink supply path 42, and a filter 43.

The ink storage container 41 is mounted at a different position from thecarriage 21, and is accommodated in an ink storage containeraccommodation portion (not illustrated) provided on an outer side(outside a movement range of the carriage 21) of a main body of theprinter 1. The ink storage container 41 and the head 31 (carriage 21)are connected to each other by the ink supply path 42. In this case, theink storage container 41 does not move.

The ink storage container 41 has a structure in which the atmosphere andthe ink can be in contact. In other words, the ink supply system of theabove-described embodiment B allows the ink stored in the ink storagecontainer 41 to include bubbles. Therefore, according to the ink supplysystem and the recording apparatus of the embodiment B provided with thesame, regardless of performing deaeration processing or not, it ispossible to store the ink which includes bubbles and has high dissolvednitrogen, in the ink storage container 41. Furthermore, the ink storagecontainer 41 makes it easy to supply more (replenish, refill) ink.Examples of the ink storage container 41 are not particularly limited ifthe container is a known container in the related art which can storethe ink, but can include an ink tank (with a high capacity) and an opentype ink cartridge. Therefore, the above-described ink supply system andrecording apparatus exhibit an extremely excellent effect in such a typeof printer as the off-carriage type serial printer.

Although not illustrated in the drawings, four ink storage containers 41may store the inks which correspond to the colors stored in the foursub-tanks 22. In other words, specific examples of the four ink storagecontainers 41 can include each ink storage container 41 which stores theblack ink, the cyan ink, the magenta ink, and the yellow ink,respectively. The level of the liquid surface of the inks can beconfirmed for each ink storage container from a predetermined part, fromthe outside. In addition, the ink storage container 41 is oneconstituent element of the printer 1, but there is less spacerestriction since the ink storage container 41 is provided on theoutside of the main body of the printer 1. Accordingly, it is possibleto store a greater volume of ink than the sub-tank 22.

The ink supply path 42 is an ink flow path for connecting the inkstorage container 41 and the head 31 to each other and for supplying theink in the ink storage container 41 to the head 31. The ink supply path42 can connect the ink storage container 41 which can store each colorof ink and the sub-tank 22 for storing the ink having a correspondingcolor, to each other. The ink supply path 42 can be formed of a memberhaving flexibility, such as synthetic rubber, and can be called a hoseor a tube. When the ink is discharged from the head 31 and the ink ofthe sub-tank 22 is consumed, the ink in the ink storage container 41 issupplied to the sub-tank 22 via the ink supply path 42. Accordingly, theprinter 1 can continue printing without a stopping operation for a longtime.

In addition, the ink storage container 41 and the ink supply path 42will be described in detail in FIG. 3 which will be described later.

The filter 43 is provided in the middle of the flow path of the inksupply path 42. When the ink which flows through the ink supply path 42includes bubbles, the filter 43 can prevent the bubbles from flowinginto the head by capturing the bubbles. Accordingly, both ink fillinginto the head 31 and ink discharging from the head 31 are performedexcellently, and both initial filling characteristics and continuousprinting stability become excellent.

An installation position of the filter 43 is not particularly limited,and for example, the filter 43 may be provided in the vicinity of anoutlet (liquid outlet portion 306) of the ink storage container 41. Inthe tank, the bubbles are likely to be generated when the inside isfilled with the ink or the ink is consumed. By suppressing the flow ofthe bubbles in the flow path, it is possible to make the initial fillingcharacteristics and the continuous printing stability superior. Inaddition, a plurality of filters 43 may be provided. However, in orderto maintain the flow of the ink well, the number of filters provided inthe middle of one flow path is preferably 1 to 3, and 1 is morepreferable.

In order to prevent nozzle omission caused by ejection of bubbles fromthe nozzle of the head 31, it is preferable that an average porediameter of the filter 43 be equal to or less than a nozzle diameter ofthe nozzle of the head 31. The nozzle diameter is generally 10 μm to 30μm. Here, the “average pore diameter of the filter” in the specificationmeans that 50% of beads which has the same diameter as the average porediameter can be eliminated. In addition, the “nozzle diameter” in thespecification means a diameter of the most slender part in the nozzle.

Examples of a material of the filter 43 are not limited to thosedescribed below, but can include stainless steel (mesh), a resin(non-woven fabric, maps), such as polypropylene. Among these, it ispreferable that the material of the filter 43 be a resin since it iseasy to capture impurities, such as foreign substances that can begenerated in the flow path, caused by the resin or rubber member whichforms the tank or the tube. By capturing the impurities and the bubblesby the filter 43, it is possible to prevent impurities attached tobubbles or impurities from being carried to the nozzles of the head 31independently and generating nozzle omission. In other words, by makingthe material of the filter 43 with the above-described preferablematerial, it is possible to make the initial filling characteristics andthe continuous printing stability superior.

The detector group 50 includes a linear type encoder (not illustrated),a rotary type encoder (not illustrated), a paper detection sensor 53,and an optical sensor 54. The linear type encoder detects a position ofthe movement direction of the carriage 21. The rotary type encoderdetects rotation of the transport roller 13. The paper detection sensor53 detects a position of a tip end of the recording medium, such as thepaper sheet, which is being supplied. The optical sensor 54 detects apresence or absence of the recording medium by a light emitting portionand a light receiving portion which are attached to the carriage 21. Theoptical sensor 54 can detect a position of an end portion of therecording medium while being moved by the carriage 21, and can detect awidth of the recording medium. In addition, according to the situation,the optical sensor 54 can even detect the tip end (an end portion of adownstream side in the transporting direction, also called an “upperend”) of the recording medium or a rear end (an end portion of anupstream side in the transporting direction, also called a “lower end”)of the recording medium.

The controller 60 is a control unit (control portion) for performingcontrol of the printer 1. The controller 60 includes an interfaceportion 61, a CPU 62, a memory 63, and a unit control circuit 64. Theinterface portion 61 performs transmitting and receiving of data betweenthe computer 110 which is the external apparatus and the printer 1. TheCPU 62 is an arithmetic processor for performing control of the entireprinter 1. The memory 63 is for securing an area where programs of theCPU 62 are accommodated or an operation area, and has a memory element,such as a RAM or an EEPROM. The CPU 62 controls each unit via the unitcontrol circuit 64 along the programs which are accommodated in thememory 63.

When performing the recording, by the control of the controller 60, adot forming operation which discharges the ink from the head 31 whilemoving in the movement direction as described below and a transportingoperation which transports the recording medium in the transportingdirection, are alternately repeated, and it is possible to print animage made of a plurality of dots on the recording medium.

In this manner, the ink jet recording apparatus of the embodiment Bprovided with the above-described ink supply system forms an image in anarea facing the head 31 of the recording medium.

2. Operation of Recording Apparatus

Examples of the operation of the recording apparatus of the embodiment Bcan include a recording operation which forms an image by attaching inkonto the recording medium and the transporting operation whichtransports the recording medium. The recording apparatus of theembodiment B performs the recording by alternately performing therecording operation and the transporting operation. During therecording, the recording medium is not transported and is in a state ofbeing held on the platen 14 which is positioned in the recording area.Examples of the above-described recording operation are not limited tothose described below, but can include an ink supplying operation whichsupplies ink from the ink storage container 41 to the head 31, an airintroducing operation which introduces the atmospheric air (air) to theink storage container 41 for supplying the ink stably to the head 31from an ink tank 44, and a discharging operation which discharges theink from the head 31 toward the recording medium. By the operation ofthe recording apparatus, it is possible to form a predetermined image inan area facing the head 31 on the recording medium.

In addition, the above-described ink supplying operation includes anoperation which supplies more (replenishes) ink to the ink storagecontainer 41 by as much as an amount of reduction after supply. Inaddition, the operation of the recording apparatus of the embodiment Bcan be called the ink jet recording method by using the ink supplysystem, and various operations including the above-described operationsof the recording apparatus can be called a “process”.

Hereinafter, the recording medium which is used in the recordingoperation in the embodiment B will be described, and then, an example ofthe recording operation will be described.

2-1. Recording Medium

Examples of the recording medium are not particularly limited, but caninclude a recording medium with ink absorbing properties. Examples ofthe recording medium with ink absorbing properties are not particularlylimited, but can include a plain paper sheet, such as anelectrophotographic paper sheet having a high penetrability of theaqueous ink, an ink jet paper sheet (an ink jet dedicated paper sheetwhich is provided with an ink absorbing layer made of silica particlesand alumina particles, or an ink absorbing layer made of a hydrophilicpolymer, such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)),an art paper sheet which is used in general offset printing havingrelatively low penetrability of the aqueous ink, a coated paper sheet,or a cast paper sheet.

2-2. Ink Supplying Operation

The recording operation in the embodiment B includes the ink supplyingoperation. The ink supplying operation supplies the ink to the head 31from the ink storage container 41 and can use the above-described inksupply system of the embodiment B. The ink supply operation will bedescribed in detail later.

2-3. Air Introducing Operation

The recording operation in the embodiment B may further include the airintroducing operation. The air introducing operation assists theabove-described ink supplying operation, and can use the above-describedink supply system of the embodiment B. For example, as described above,in the recording operation which uses the ink supply system providedwith an air introducing flow path for introducing air and the inkstorage container having a structure in which bubbles are generated inthe ink, the air introducing operation is performed. The air introducingoperation introduces the atmospheric air (air) to the ink storagecontainer 41 in order to stably supply the ink to the head 31 from theink tank 44. In addition, the air introducing operation will bedescribed in detail later.

2-4. Discharging Operation

The recording operation in the embodiment B includes the dischargingoperation. In the ink jet recording method, the discharging operationdischarges the ink droplets onto the recording medium, and forms animage. As the method of discharging, it is possible to use already knownmethods in the related art. Among the methods, when a method (arecording method which uses a head that forms the ink droplets bymechanically deforming an electrostrictive element) of discharging thedroplets from the nozzle by using vibration of a piezoelectric elementor a method of discharging the ink from the nozzle by using a heatingunit and generating bubbles in the head are used, excellent recordingcan be performed. In addition, various discharging conditions, such as adischarging temperature, a discharging time, or a viscosity of thedischarged ink, are not particularly limited.

Hereinafter, among the recording operations in the embodiment B, the inksupplying operation and the air introducing operation will be mainlydescribed in detail.

FIG. 3 is a schematic view for describing a principle of ink supply tothe head 31 from the ink tank 44 which is an example of the ink storagecontainer 41. A technique of ink supplying illustrated in FIG. 3 is,simply in other words, a technique which uses a principle of theMariotte bottle. In the technique, as the head 31 and the ink tank 44are connected to each other via the sub-tank 22 and the ink supply path42 which are provided in the carriage 21, and negative pressure isgenerated inside the sub-tank 22, the ink is absorbed and supplied tothe head 31 from the ink tank 44. FIG. 3 schematically illustratesmainly the inside of the ink tank 44, the ink supply path 42, and thesub-tank 22.

The printer 1 is installed on a predetermined horizontal surface sf. Theliquid outlet portion 306 of the ink tank 44 and a liquid receivingportion 202 of the sub-tank 22 are connected to each other via the inksupply path 42.

The sub-tank 22 is molded using a synthetic resin, such as polystyreneor polyethylene. The sub-tank 22 includes an ink storage chamber 204, anink flowing path 208, and a filter 206. An ink feeding needle 21 a ofthe carriage 21 is inserted into the ink flowing path 208. Whenimpurities, such as foreign substances, blend with the ink which flowsthrough the ink flowing path 206, the filter 206 prevents the impuritiesfrom flowing into the head 31 by capturing the impurities. The ink ofthe ink storage chamber 204 flows through the ink flowing path 208 andthe ink feeding needle 21 a by the absorption of the head 31, and issupplied to the head 31. By being discharged and attached to therecording medium via the nozzle, the ink supplied to the head 31 formsan image (the above-described discharging operation).

Here, as described in the embodiment B, even when the sub-tank 22 isprovided between the ink storage container 41 and the head 31, since theink supply path 42 connects the ink storage container 41 and the head 31to each other, the ink supply path 42 exists even in the sub-tank 22.For this reason, in the above-described case, any of the filter 43 andthe filter 206 corresponds to the filter which is provided in ink supplypath 42.

FIG. 3 is one preferable aspect in which the filter 206 is provided inthe flow path in the sub-tank 22. Accordingly, since the collectedbubbles remain in a space on the upper end of the sub-tank 22, closingof the flow path by the gathered bubbles is unlikely to happen. Inaddition, an aspect in which the filter 43 and the filter 206 areprovided together as illustrated in FIG. 3 may be employed, and anaspect in which only the filter 206 is provided may be employed.

In addition, in another preferable aspect, by providing the filter 43right in front (upstream side) of the head 31, it is possible toeffectively collect the bubbles generated right in front (upstream side)of the head 31. For example, an aspect in which the filter is providedon the inside of the ink feeding needle 21 a, where there is equippingof the sub-tank 22, can be employed. According to the aspect, it ispossible to effectively collect the bubbles generated when attaching anddetaching the cartridge. In addition, even in the aspect in which thefilter is provided inside the ink feeding needle, it is possible toprovide a plurality of filters.

The ink tank 44 supplies the ink to the head 31 of the printer 1 byusing the principle of the Mariotte bottle. An outer surface of the inktank 44 is made of a first wall 370C1, a second wall (upper surfacewall) 370C2, and a lower surface wall 370C3. The ink tank 44 has the airintroducing flow path and the ink flow path on the inside thereof. Theair introducing flow path is a flow path for introducing the air to aliquid storage chamber 340 through an atmospheric air introduction port318 via an atmosphere flow path (not illustrated) from an atmosphereopening port 317. The air introducing flow path is a flow path forperforming a pouring (including “replenishment”, the same applies to thefollowing) of the ink to the liquid outlet portion 306 through theliquid storage chamber 340 from an ink flow path liquid pouring path304.

First, the above-described air introducing flow path is a flow pathwhich is used in the above-described air introducing operation. The airintroducing flow path includes an atmosphere opening port 317 which isopen to the outside (atmosphere), an air storage chamber 330 which hasthe atmospheric air introduction port 318 as one end thereof and an airchamber side opening 351 as the other end thereof, and a liquid chambercommunication path 350 which has the air chamber side opening 351 as oneend thereof and an air introducing port 352 as the other end thereof.The atmosphere opening port 317 communicates with the atmosphere, theair storage chamber 330 opens in the atmospheric air introduction port318 which is one end thereof, and the atmosphere opening port 317 andthe atmospheric air introduction port 318 communicate with each othervia the flow path (not illustrated). In other words, the air storagechamber 330 communicates with the outside (atmosphere). In the liquidchamber communication path 350, the air chamber side opening 351 whichis one end thereof opens in the air storage chamber 330, and the airintroducing port 352 which is the other end thereof opens in the liquidstorage chamber 340. In other words, the air storage chamber 330communicates with the liquid storage chamber 340. In addition, it ispreferable that the liquid chamber communication path 350 have a smallflow path cross-sectional area which can form a meniscus (liquid surfacecross-linking).

In this manner, in the above-described air introducing flow path, theair introducing port 352 which is one end thereof opens in the liquidstorage chamber 340, and the atmosphere opening port 317 which is theother end thereof is open to the outside. In other words, in a statewhere the ink tank 44 which will be described later is in a use state, aliquid surface which is directly in contact with the atmosphere isformed in the liquid chamber communication path 350 (specifically, inthe vicinity of the air introducing port 352), and the air (bubbles G)is introduced into the liquid storage chamber 340 as the air (bubbles)is introduced into the ink of the liquid storage chamber 340 from theair introducing port 352. Accordingly, as described later, it ispossible to stably supply the ink to the head 31 from the ink tank 44.In other words, the air introducing operation which has been describedup to here is performed for stabilizing the ink supplying operationwhich will be described later.

Meanwhile, the above-described ink flow path is used in theabove-described ink supplying operation. The ink supplying operation isperformed according to the reduction of an amount of stored ink in theink tank 44 caused by the discharging operation from the head 31, and isperformed more stably by the above-described air introducing operation.

Here, the ink tank 44 has a use state and a pouring state. The “usestate” is a state of the ink tank 44 which is installed on thehorizontal surface when the ink is supplied to the head 31 of theprinter 1. In other words, in the use state, the liquid pouring path 304is open in a horizontal direction (but, the opening is closed by a plugmember 302). FIG. 3 illustrates the ink tank 44 in the use state. Inaddition, in the use state, the liquid storage chamber 340 and the airstorage chamber 330 are arranged in parallel in the horizontaldirection. Furthermore, in the use state, the air introducing port 352is positioned below the liquid surface of the liquid which is stored inthe liquid storage chamber 340. Meanwhile, the “pouring state” is astate of the ink tank 44 which is installed on the horizontal surfacewhen the ink is injected into the ink tank 44. In other words, in thepouring state, the liquid pouring path 304 is open upward. In addition,in the pouring state, the liquid storage chamber 340 and the air storagechamber 330 are arranged in parallel in a vertical direction.Furthermore, in the pouring state, the air introducing port 352 ispositioned above the liquid surface of the liquid which is stored in theliquid storage chamber 340 when a liquid volume at a time when theliquid surface of the liquid stored in the liquid storage chamber 340 ison a straight line LM1 in the use state (“first state display line LM1”)is stored in the liquid storage chamber 340.

In the above-described pouring state, when an ink liquid surface reachesthe vicinity of a straight light LM2 (“second state display line LM2”)which is horizontal in the pouring state, a user may stop thereplenishment of the ink. After the ink is poured into the liquidstorage chamber 340 from the liquid pouring path 304 in this manner, theliquid pouring path 304 is sealed by the plug member 302. Furthermore,the liquid storage chamber 340 is maintained at negative pressure as theink of the liquid storage chamber 340 is absorbed from the head 31.

In the above-described use state, the air introducing port 352 ispositioned on a lower side of the first state display line LM1. The airintroducing port 352 in FIG. 3 is formed on the lower surface wall 370C3which interposes the liquid storage chamber 340 and is positioned on thelower side in the use state, in a container main body 45 whichpartitioned and forms the liquid storage chamber 340. Accordingly, evenwhen the ink of the liquid storage chamber 340 is consumed, and theliquid surface of the liquid storage chamber 340 lowers, a liquidsurface (atmosphere contact liquid surface) LA which is in contact withthe atmosphere maintains a certain height for a long time (time for theink liquid surface to reach the first state display line LM1). Inaddition, in the use state, the air introducing port 352 is disposed tobe at a position which is lower than the head 31. Accordingly, a waterhead difference d1 is generated. In addition, in the use state,hereinafter, the water head difference d1 in a state where theatmosphere contact liquid surface LA which is the meniscus in thevicinity of the air introducing port 352 of the liquid chambercommunication path 350 is formed is called a “steady state water headdifference d1”.

As the ink of the ink storage chamber 204 is absorbed by the head 31,the ink storage chamber 204 has equal to or higher than predeterminednegative pressure. When the ink storage chamber 204 has equal to orhigher than predetermined negative pressure, the ink of the liquidstorage chamber 340 is supplied to the ink storage chamber 204 via theink supply path 42. In other words, more ink in an amount flowing out tothe head 31 is automatically supplied (replenished) from the liquidstorage chamber 340 to the ink storage chamber 204. In other words, anabsorption power (negative pressure) from the head 31 side is greaterthan the water head difference d1 which is generated by a difference ofheights in the vertical direction between the air storage chamber 330 inthe ink tank 44, that is, the atmosphere contact liquid surface (inkliquid surface) LA which is in contact with the atmosphere and a nozzlesurface of the head 31, to a certain extent. As a result, the ink issupplied to the ink storage chamber 204 from the liquid storage chamber340.

When the ink of the liquid storage chamber 340 is consumed, the air ofthe air storage chamber 330 is introduced as the bubbles G to the liquidstorage chamber 340 via the liquid chamber communication path 350. Inother words, in the liquid storage chamber 340 of the ink tank 44, theatmosphere which is introduced through the above-described airintroducing flow path comes in contact with the ink poured through theabove-described ink flow path. Accordingly, an ink liquid surface LF ofthe liquid storage chamber 340 lowers. Meanwhile, since a height of theatmosphere contact liquid surface LA which is in contact with theatmosphere is maintained to be constant, the water head difference d1 ismaintained to be constant. In other words, by a predetermined absorptionforce of the head 31, it is possible to stably provide the ink to thehead 31 from the ink tank 44 from the viewpoint of an ink amount.

In this manner, the ink tank 44 can stably supply the ink, but a problemoccurs in that a part of the bubbles G flows out to the liquid outletportion 306 together with the ink and carried to the head 31, and afailure, such as dot omission, can be generated. In detail, asillustrated in the drawing surrounded by a square on an upper left sideof FIG. 3, when the bubbles G are generated in the ink from the airintroducing port 352, there is a case where the bubbles G split andmicrobubbles Gb are generated which are considerably small with respectto a size of the air introducing port 352, regardless of a bubble Gawhich has a size that is generally assumed. In the ink tank 44, themicrobubbles Gb have a diameter of an extent of several+μm, for example.A buoyancy of the microbubbles Gb is small (for example, 0.1 mm/s), andin particular, is likely to be influenced by the flow of the ink of theliquid storage chamber 340. When continuous printing is performed byusing a high Duty of the printer 1, the microbubbles Gb flow into thehead 31 side of the printer 1 via the liquid outlet portion 306 alongthe flow of the ink, and a failure, such as dot omission, is likely tooccur.

Here, as a result of further examination of the inventors, it was foundthat it is possible to capture the microbubbles Gb included in the inkby the filter 43 and to prevent the microbubbles Gb from flowing intothe head 31, by providing the filter 43 in the middle of the flow pathof the ink supply path 42 and making the ink composition a predeterminedcomposition. Accordingly, the above-described ink supply system of theembodiment B and the recording apparatus of the embodiment B providedwith the same can be excellent in discharging, and can have excellentcontinuous printing stability.

Furthermore, in the off-carriage type serial printer, a failure, such asdot omission, is likely to occur, which is caused by an ink supplycontainer, such as the ink tank 44 having a structure in which theatmospheric air introduced from the outside comes into contact with theink for stabilizing the ink supplying. Therefore, when theabove-described ink supply system and the recording apparatus providedwith the same are employed in the off-carriage type serial printer, theink which will be described later actively takes in the bubbles attachedto members, such as the ink storage container 41 or the ink supply path42, and can include the bubbles, such as the microbubbles Gb, which arenot preferable. However, when the ink in which the bubbles areincorporated passes through the filter 43 of the ink supply path 42, thefilter 43 captures the bubbles taken in by the ink, and the bubbles canbe eliminated from the ink. For this reason, the ink which does notinclude the bubbles is supplied to the head 31, and thus, it is possibleto prevent a failure, such as dot omission, from occurring. Therefore,when the above-described ink supply system and the recording apparatusprovided with the same are employed in the off-carriage type serialprinter, an extremely excellent effect is achieved.

3. Modification Example

Specific examples of the above-described ink supply system of theembodiment B and the recording apparatus provided with the same of theembodiment B are not limited to the description up to here, and it ispossible to apply various changes without departing from the scope ofthe present invention. For example, a modification example as followscan be given.

In the recording apparatus of the embodiment B, the ink may not beabsorbed and supplied to the head 31 from the ink tank 44 as thenegative pressure is generated inside the sub-tank 22, and the ink maybe supplied to the head 31 by applying pressure by a pump from the inktank 44. In addition, as described above, without providing the sub-tank22, the ink tank 44 and the head 31 may be connected to each other viathe ink supply path 42.

In addition, a type of the recording apparatus of the embodiment B maybe the on-carriage type serial printer which has the ink cartridge (inktank, not illustrated) together with the head 31 on the carriage 21. Ina case of the on-carriage type, the carriage 21 holds the ink cartridge(not illustrated) which stores the ink, which is detachable. Inparticular, when the ink cartridge (not illustrated) has an open typestructure so that an inflow of the atmospheric air is not blocked, theabove-described ink supply system and the recording apparatus providedwith the same achieves a notably great effect. In addition, the inkcartridge (not illustrated) in the on-carriage type serial printer mayhave the same structure as the above-described sub-tank 22.

In addition, the on-carriage type serial printer may install morehigh-capacity ink tanks (not illustrated) on the outside thereof. Thehigh-capacity ink tank can be connected with the above-described inkcartridge via the ink supply path (not illustrated). Accordingly, thestorage amount of the ink can be increased drastically. In addition, thehigh-capacity ink tank and the ink supply path may have the samestructure as the above-described ink tank 44 and the ink supply path 42.When more ink tanks are installed on the outside, since the same problemas the problem caused by the above-described ink tank 44 can occur, theabove-described ink supply system and the recording apparatus providedwith the same achieve a notably great effect.

In addition, the recording apparatus of the embodiment B may be a lineprinter.

In this manner, according to the above-described embodiment B and themodification example, even in a case of ink (dissolved nitrogen is equalto or higher than 5 ppm, for example) which includes bubbles, it ispossible to provide an ink supply system and an ink jet recordingapparatus provided with the same which have excellent initial fillingcharacteristics and continuous printing stability.

Ink

One embodiment of the present invention relates to the ink. The ink isused in the above-described ink supply system of the embodiment B andthe ink jet recording apparatus provided with the same. The ink includesthe alkylene oxide adduct (A) of acetylenic glycol in which the mainchain has 12 or more carbon atoms, and polyoxyalkylene alkyl ether (C).The AO adduct of acetylenic glycol in which the main chain has 12 ormore carbon atoms included in the ink gives the ink an excellentwettability, and takes bubbles attached to surfaces of members, such asthe ink storage container or the ink supply path, into the ink. Inaddition, the above-described filter captures the bubbles taken into theink and eliminates the bubbles from the ink.

Hereinafter, additives (components) which are included or can beincluded in the ink of the embodiment B will be described.

Alkylene Oxide Adduct (A) of Acetylenic Glycol in which Main Chain has12 or More Carbon Atoms

The ink composition of the embodiment B includes the alkylene oxideadduct (A) of acetylenic glycol in which the main chain has 12 or morecarbon atoms in the above-described embodiment A. Therefore, specificexamples or a preferable content are also the same as in a case of theabove-described embodiment A.

Polyoxyalkylene Alkyl Ether (C)

The ink of the embodiment B includes polyoxyalkylene alkyl ether (C) inthe above-described embodiment A. Therefore, specific examples or apreferable content are also the same as in a case of the above-describedembodiment A.

Surfactant Other than Those Described Above

The ink in the embodiment B may include a surfactant (hereinafter,referred to as “the other surfactant”) other than those described above.

Acetylenic Glycol (B) in which Main Chain has 10 or More Carbon Atoms

It is preferable that the ink of the embodiment B include acetylenicglycol (B) in which the main chain has 10 or more carbon atoms in theabove-described embodiment A. Among the acetylenic glycol-basedsurfactants, acetylenic glycol in which the main chain has 10 or morecarbon atoms can effectively eliminate the bubbles generated in the ink.Accordingly, the initial filling characteristics and the continuousprinting stability becomes superior. In addition, specific examples or apreferable content are also the same as in a case of the above-describedembodiment A.

Coloring Agent

It is preferable that the ink in the embodiment B further include acoloring agent. The specific examples or a preferable content are thesame as in the above-described embodiment A.

Water

The ink in the embodiment B may contain water. The specific examples ora preferable content are the same as in the above-described embodimentA.

Organic Solvent

It is preferable that the ink in the embodiment B further include anorganic solvent. The specific examples or a preferable content are thesame as in the above-described embodiment A.

Other Components

In addition to the above-described materials, the ink of the embodimentB may further include a pH adjuster, such as triethanolamine ortripropanolamine, a preservative and a fungicide, a rust preventive, ora chelating agent.

Method of Manufacturing Ink

The ink of the embodiment B can be manufactured in the same manner as ina case of the above-described embodiment A.

In this manner, according to the embodiment B, it is possible toappropriately use the ink supply system and the ink jet recordingapparatus provided with the same which have excellent initial fillingcharacteristics and continuous printing stability, and furthermore, toprovide ink which is excellent in dissolution stability and preservationstability.

EXAMPLES

Hereinafter, examples of the present invention will be described indetail, but the present invention is not limited thereto.

Example A Materials Used

Main materials used in the examples and comparative examples below areas follows.

Dye

-   -   C. I. direct blue 199 (hereinafter, described as a “blue dye”)

Surfactant

1. Alkylene Oxide Adduct of Acetylenic Glycol in which Main Chain has 12or More Carbon Atoms

-   -   Surfactant 1 (12 carbon atoms in the main chain, ethylene oxide        is added, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol ethoxylate)        2. Acetylenic Glycol in which Main Chain has 10 or More Carbon        Atoms    -   Surfactant 2 (12 carbon atoms in the main chain, ethylene oxide        is not added, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol)    -   Surfactant 3 (10 carbon atoms in the main chain, ethylene oxide        is not added, 2,4,7,9-tetramethyl-5-decyne-4,7-diol)

3. Other Acetylenic Glycol-Based Compounds

-   -   Surfactant 4 (10 carbon atoms in the main chain, the number of        additional moles of ethylene oxide is        10,2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate)    -   Surfactant 5 (10 carbon atoms in the main chain, the number of        additional moles of ethylene oxide is        4,2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate)    -   Surfactant 6 (8 carbon atoms in the main chain, ethylene oxide        is not added, 3,6-dimethyl-4-octyne-3,6-diol)

Polyoxyalkylene Alkyl Ether

-   -   Polyoxyalkylene alkyl ether 1 (HLB value is 15.0, hereinafter,        referred to as a “POAAE1”)

In addition, a chemical formula of the POAAE1 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w+y=15, and x+z=4.

-   -   Polyoxyalkylene alkyl ether 2 (HLB value is 12.0, hereinafter,        referred to as a “POAAE2”)

In addition, a chemical formula of the POAAE2 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w=7, and x=5.

-   -   Polyoxyalkylene alkyl ether 3 (HLB value is 10.9, hereinafter,        referred to as a “POAAE3”)

In addition, a chemical formula of the POAAE3 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w=5, and x=4.

Organic Solvent

-   -   Triethylene glycol    -   Triethylene glycol monobutyl ether (hereinafter, referred to as        “TEGmBE”)    -   Propylene glycol    -   Dipropylene glycol    -   Glycerin    -   Triethanolamine

Examples 1A to 9A, comparative examples 1A to 8A, reference Examples 1Ato 2A

Each ink composition was prepared according to the compositionillustrated in Table 1 and Table 2 described below by mixing in eachcomponent and stirring. In addition, miscellaneous materials wereremoved from each ink composition by filtering with a membrane filterhaving a pore diameter of 1 μm. In addition, in Table 1 and Table 2shown below, the unit of the numeric values is mass %, and the sum is100.00 mass %.

TABLE 1 Table 1 Example No. Component 1A 2A 3A 4A 5A 6A 7A 8A 9A Bluedye 4 4 4 4 4 4 4 4 4 Triethylene glycol 10 10 10 10 10 10 10 10 10TEGmBE 8 8 8 8 8 8 8 8 8 Propylene glycol 1 1 1 1 1 1 1 1 1 Dipropyleneglycol 1 1 1 1 1 1 1 1 1 Glycerin 10 10 10 10 10 10 10 10 10Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Surfactant 1 0.1 0.10.1 0.1 0.1 0.3 0.3 0.4 0.3 Surfactant 2 0.1 0.1 0.1 — — 0.1 0.3 0.3 0.4Surfactant 3 — — — 0.1 0.1 — — — — Surfactant 4 — — — — — — — — —Surfactant 5 — — — — — — — — — Surfactant 6 — — — — — — — — — POAAE10.05 — — 0.05 — 0.05 0.3 0.3 0.3 POAAE2 — 0.05 — — 0.05 — — — — POAAE3 —— 0.05 — — — — — — Ion exchanged water Residual Residual ResidualResidual Residual Residual Residual Residual Residual quantity quantityquantity quantity quantity quantity quantity quantity quantity Sum100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

TABLE 2 Table 2 Comparative example and reference example No.Comparative example Reference example Component 1A 2A 3A 4A 5A 6A 7A 8A1A 2A Blue dye 4 4 4 4 4 4 4 4 4 4 Triethylene glycol 10 10 10 10 10 1010 10 10 10 TEGmBE 8 8 8 8 8 8 8 8 8 8 Propylene glycol 1 1 1 1 1 1 1 11 1 Dipropylene glycol 1 1 1 1 1 1 1 1 1 1 Glycerin 10 10 10 10 10 10 1010 10 10 Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Surfactant 1 0.1 — — 0.1 0.1 0.1 Surfactant 2 — 0.1 — 0.1 — — 0.1 — — —Surfactant 3 — — — — — — — 0.1 0.1 0.1 Surfactant 4 — — — — — — — 0.10.1 0.1 Surfactant 5 — — — — — — 0.1 — — — Surfactant 6 — — — — — 0.1 —— — — POAAE1 — — 0.05 0.05 0.05 0.05 0.05 0.05 0.05 POAAE2 — — — — — — —— — — POAAE3 — — — — — — — — — — Ion exchanged water Residual ResidualResidual Residual Residual Residual Residual Residual Residual Residualquantity quantity quantity quantity quantity quantity quantity quantityquantity quantity Sum 100.00 100.00 100.00 100.00 100.00 100.00 100.00100.00 100.00 100.00

Measurement and Evaluation Methods 1A. Measurement of Dissolved Nitrogenof Ink

Dissolved nitrogen was measured by using a 6890N Network GC manufacturedby Agilent Technologies. The measurement results are illustrated inTable 3 described below.

Here, the deaeration processing was performed only with respect to eachof ink compositions of the reference examples, and was not performedwith respect to each of ink compositions of the examples and thecomparative examples. The deaeration processing in the referenceexamples used a chamber type vacuum deaeration apparatus which isavailable on the market, and adjusts the deaeration time. Accordingly,each of inks that had different dissolved nitrogen from each of otherswas prepared.

In addition, the “dissolved nitrogen” in Table 3 shown below representsan amount of nitrogen which is dissolved in the ink composition, and theunit thereof is ppm.

2A. Evaluation of Dissolution Stability

A visual observation on the each prepared ink composition was performedto check whether the material components were dissolved (dispersed)uniformly or not.

Evaluation standards were as follows. The evaluation results areillustrated in Table 3 shown below.

B: Raw material components of the ink were dissolved (dispersed)uniformly, and undissolved floating materials were not observed.

D: Raw material components of the ink were not dissolved (dispersed),and undissolved floating materials were observed.

3A. Evaluation of Preservation Stability

Each prepared ink composition was divided by a 20 ml glass bottle with alid, and was left for one week at 70° C. The liquid surface of the inkwas observed, and presence or absence of floating materials was visuallychecked. Furthermore, when the ink was filtered with a filter having apore diameter of 10 μm, the presence or absence of collected materials(filtered materials) was checked.

Evaluation standards were as follows. The evaluation results areillustrated in Table 3 shown below.

B: Floating materials derived from the ink components were not observed,and collected materials were not obtained.

C: Floating materials derived from the ink components were observed, butcollected materials were not obtained (practically no problem).

D: Collected materials were obtained.

4A. Evaluation of Initial Filling Characteristics

The ink tank of an ink jet printer (L100 [name of product], manufacturedby Seiko Epson Corporation) was filled with the each prepared inkcomposition. An initial filling operation was performed to the headaccording to an initial filling sequence determined by L100. After that,in order to check whether or not the ink was discharged from all of thenozzles of the head, a nozzle check was performed. When there arenozzles which could not discharge ink, a cleaning (absorption of the inkin the nozzles) of the head was performed, and after that, the nozzlecheck was performed again. Based on the number of times of cleaningrequired until the ink could be discharged from all of the nozzles, theinitial filling characteristics were evaluated according to thefollowing evaluation standards. The evaluation results are illustratedin Table 3 shown below.

B: The ink was discharged from all of the nozzles simply by the initialfilling sequence.

C: The number of times of cleaning required until the ink could bedischarged from all of the nozzles was 1.

D: The number of times of cleaning required until the ink could bedischarged from all of the nozzles was 2.

5A. Evaluation of Continuous Printing Stability

According to the above-described “4A. Evaluation of initial fillingcharacteristics”, after confirming that the ink could be discharged fromall of the nozzles of the head, when an image of 70% Duty was printed byusing each ink composition and a plain paper sheet (P paper sheet [nameof product], manufactured by Fuji Xerox Co., Ltd.) of A4 size, theevaluation of continuous printing stability was performed. The totalnumber of printed paper sheets was 1,000 since the continuous printingwith 500 paper sheets was performed twice. After that, the nozzle checkwas performed, and the continuous printing stability was evaluated bythe following evaluation standards, based on the number of times ofnozzle omission. The evaluation results are illustrated in Table 3 shownbelow.

B: The number of times of generation of nozzle omission was 1 or less.

C: The number of times of generation of nozzle omission was 2.

D: The number of times of generation of nozzle omission was 3 or more.

TABLE 3 Table 3 Example No. Reference Example Comparative exampleexample Items 1A 2A 3A 4A 5A 6A 7A 8A 9A 1A 2A 3A 4A 5A 6A 7A 8A 1A 2ADissolved nitrogen 8.7 8.2 7.7 7.8 8.3 8.7 8.7 8.7 8.7 8.1 8.2 8.2 8.48.4 8.0 8.3 7.9 5.5 1.4 Dissolution stability B B B B B B B B B D D B DB B B B B B Preservation stability B B B B B B B C C D D B D B D B B B BInitial filling B B C B B B B B B D D D D D D D D C B characteristicsContinuous printing B B C B B C B B B D D D D D D D D C B stability

According to the results in Table 3 shown above, it was found that theink composition (each example) including the alkylene oxide adduct (A)of acetylenic glycol in which the main chain has 12 or more carbonatoms, acetylenic glycol (B) in which the main chain has 10 or morecarbon atoms, and polyoxyalkylene alkyl ether (C) has excellent initialfilling characteristics and continuous printing stability, and even hasexcellent dissolution stability and a preservation stability, comparedto the ink composition (each comparative example) which does not includealkylene oxide adduct (A), acetylenic glycol (B), and polyoxyalkylenealkyl ether (C). In addition, in all of the above-described examples,the deaeration was not performed at all, but it was found that the inkcomposition (each comparative example) is the same or superior in anyone of the initial filling characteristics, the continuous printingstability, the dissolution stability, and the preservation stabilitycompared with the ink composition (each reference example, the inkcomposition itself corresponds to the comparative example) in which thedeaeration processing was performed.

Example B Materials Used

Main materials used in the examples and comparative examples below wereas follows.

Pigment

-   -   C. I. direct blue 199

Surfactant

1. Alkylene Oxide Adduct of Acetylenic Glycol in which Main Chain has 12or More Carbon Atoms

-   -   Surfactant 1 (12 carbon atoms in the main chain, ethylene oxide        is added, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol ethoxylate)        2. Acetylenic Glycol in which Main Chain has 10 or More Carbon        Atoms    -   Surfactant 2 (12 carbon atoms in the main chain, ethylene oxide        is not added, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol)    -   Surfactant 3 (10 carbon atoms in the main chain, ethylene oxide        is not added, 2,4,7,9-tetramethyl-5-decyne-4,7-diol)

3. Other Acetylenic Glycol-Based Compounds

-   -   Surfactant 4 (10 carbon atoms in the main chain, the number of        additional moles of ethylene oxide is        10,2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate)    -   Surfactant 5 (10 carbon atoms in the main chain, the number of        additional moles of ethylene oxide is        4,2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate)

Polyoxyalkylene Alkyl Ether

-   -   Polyoxyalkylene alkyl ether 1 (HLB value is 15.0, hereinafter,        referred to as a “POAAE1”)

In addition, a chemical formula of the POAAE1 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w+y=15, and x+z=4.

-   -   Polyoxyalkylene alkyl ether 2 (HLB value is 12.0, hereinafter,        referred to as a “POAAE2”)

In addition, a chemical formula of the POAAE2 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w=7, and x=5.

-   -   Polyoxyalkylene alkyl ether 3 (HLB value is 10.9, hereinafter,        referred to as a “POAAE3”)

In addition, a chemical formula of the POAAE3 is illustrated below.

RO(C₂H₄O)_(w)(C₃H₆O)_(x)H

In the above-described chemical formula, R is alkyl which has 12 carbonatoms, w=5, and x=4.

Organic Solvent

-   -   Triethylene glycol    -   Triethylene glycol monobutyl ether (hereinafter, referred to as        “TEGmBE”)    -   Propylene glycol    -   Dipropylene glycol    -   Glycerin    -   Triethanolamine

Examples 1B to 5B, Comparative Examples 1B to 5B, Reference Examples 1Bto 2B

Each ink was prepared according to the composition illustrated in Table4 and Table 5 described below by mixing in each component and stirring.In addition, miscellaneous materials were removed from each inkcomposition by filtering with a membrane filter having a pore diameterof 1 μm. In addition, in Table 4 and Table 5 shown below, the unit ofthe numeric value is mass %, and the sum is 100.00 mass %.

TABLE 4 Table 4 Example Example Example Example Example ComparativeComparative Comparative 1B 2B 3B 4B 5B example 1B example 2B example 3BPresence or absence of filter Present Present Present Present PresentAbsent Present Present C.I. Direct Blue 199 4 4 4 4 4 4 4 4 Triethyleneglycol 10 10 10 10 10 10 10 10 TEGmBE 8 8 8 8 8 8 8 8 Propylene glycol 11 1 1 1 1 1 1 Dipropylene glycol 1 1 1 1 1 1 1 1 Glycerin 10 10 10 10 1010 10 10 Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Surfactant 10.1 0.1 0.1 0.1 0.1 0.1 0.1 — Surfactant 2 — — — 0.1 — — — — Surfactant3 — — — — 0.1 — — — Surfactant 4 — — — — — — — — Surfactant 5 — — — — —— — — Surfactant 6 — — — — — — — — POAAE1 0.05 — — 0.05 0.05 0.05 — 0.05POAAE2 — 0.05 — — — — — — POAAE3 — — 0.05 — — — — — Ion exchanged waterResidual Residual Residual Residual Residual Residual Residual Residualquantity quantity quantity quantity quantity quantity quantity quantitySum 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

TABLE 5 Reference Reference Comparative Comparative example exampleexample 4B example 5B 1B 2B Presence or absence Present Present PresentPresent of filter C. I. Direct Blue 4 4 4 4 199 Triethylene glycol 10 1010 10 TEGmBE 8 8 8 8 Propylene glycol 1 1 1 1 Dipropylene glycol 1 1 1 1Glycerin 10 10 10 10 Triethanolamine 0.5 0.5 0.5 0.5 Surfactant 1 — — —— Surfactant 2 0.1 — — — Surfactant 3 — 0.1 0.1 0.1 Surfactant 4 — 0.10.1 0.1 Surfactant 5 0.1 — — — POAAE1 0.05 0.05 0.05 0.05 POAAE2 — — — —POAAE3 — — — — Ion exchanged water Residual Residual Residual Residualquantity quantity quantity quantity Sum 100.00 100.00 100.00 100.00

Measurement and Evaluation Methods 1B. Measurement of Dissolved Nitrogenof Ink

Dissolved nitrogen was measured by using a 6890N Network GC manufacturedby Agilent Technologies. The measurement results are illustrated inTable 3 shown below.

Here, the deaeration processing was performed only with respect to eachink of the reference examples 1B to 2B, and was not performed withrespect to each ink of the examples and the comparative examples. Thedeaeration processing in the reference examples 1B to 2B used a chambertype vacuum deaeration apparatus which is available on the market, andadjusts the deaeration time. Accordingly, each of inks that haddifferent dissolved nitrogen from each of others was prepared.

In addition, the “dissolved nitrogen” in Table 6 shown below representsan amount of nitrogen which was dissolved in the ink, and the unitthereof is ppm.

2B. Evaluation of Dissolution Stability

A visual observation on the each prepared ink was performed to checkwhether the material components were dissolved (dispersed) uniformly ornot.

Evaluation standards were as follows. The evaluation results areillustrated in Table 6 shown below.

B: Raw material components of the ink were dissolved (dispersed)uniformly, and undissolved floating materials were not observed.

D: Raw material components of the ink were not dissolved (dispersed),and undissolved floating materials were observed.

3B. Evaluation of Preservation Stability

Each prepared ink was divided by a 20 ml glass bottle with a lid, andwas left for one week at 70° C. The liquid surface of the ink wasobserved, and presence or absence of floating materials was visuallychecked. Furthermore, when the ink was filtered with a filter having apore diameter of 10 μm, the presence or absence of collected materials(filtered materials) was checked.

Evaluation standards were as follows. The evaluation results areillustrated in Table 6 shown below.

B: Neither floating materials nor collected materials were confirmed.

D: Floating materials or collected materials was confirmed.

4B. Evaluation of Initial Filling Characteristics

The ink tank of an ink jet printer (L100 [name of product], manufacturedby Seiko Epson Corporation) was filled with each prepared ink. Aninitial filling operation was performed to the head according to aninitial filling sequence determined by L100. After that, in order tocheck whether or not the ink can be discharged from all of the nozzlesof the head, a nozzle check was performed (the nozzle diameter of theused nozzle was approximately 22 μm). When there were nozzles whichcould not discharge ink, a cleaning (absorption of the ink in thenozzles) of the head was performed, and after that, the nozzle check wasperformed again. Based on the number of times of the cleaning requireduntil the ink could be discharged from all of the nozzles, the initialfilling characteristics were evaluated according to the followingevaluation standards. The evaluation results are illustrated in Table 6shown below.

B: The ink was discharged from all of the nozzles simply by the initialfilling sequence.

C: The number of times of cleaning required until the ink could bedischarged from all of the nozzles was 1.

D: The number of times of cleaning required until the ink could bedischarged from all of the nozzles was 2.

5B. Evaluation of Continuous Printing Stability

According to the above-described “4B. Evaluation of initial fillingcharacteristics”, after confirming that the ink could be discharged fromall of the nozzles of the head, when an image of 70% Duty was printed byusing each ink and a plain paper sheet (P paper sheet [name of product],manufactured by Fuji Xerox Co., Ltd.) of A4 size, the evaluation ofcontinuous printing stability was performed (the nozzle diameter of thenozzles used was approximately 22 μm). The total number of printed papersheets was 1,000 since the continuous printing with 500 paper sheets wasperformed twice. After that, the nozzle check was performed, and thecontinuous printing stability was evaluated by the following evaluationstandards, based on the number of times of nozzle omission. Theevaluation results are illustrated in Table 6 shown below.

A: The number of times of generation of nozzle omission was 0.

B: The number of times of generation of nozzle omission was 1.

C: The number of times of generation of nozzle omission was 2.

D: The number of times of generation of nozzle omission was 3 or more.

TABLE 6 Table 6 Example No. Reference Example Comparative exampleexample Item 1B 2B 3B 4B 5B 1B 2B 3B 4B 5B 1B 2B Dissolved 8.4 8.1 8.08.7 8.7 8.4 8.1 8.2 8.3 7.9 5.5 1.4 nitrogen Dissolution B B B B B B D BB B B B stability Preservation B B B B B B D B B B B B stability InitialB B C B B D D D D D C B filling char- acteristics Continuous B B C A A DD D D D C B printing stability

According to the results in Table 6 described above, it was found thatthe ink supply system and the ink jet recording apparatus provided withthe same (each example) which includes: the ink storage container inwhich the atmosphere and the ink can be in contact with each other; thehead for discharging the ink; the ink supply path which connects the inkstorage container and the head and in which the ink flows to the headfrom the ink storage container; and the filter (D) provided in the inksupply path, and in which the ink contains the alkylene oxide adduct (A)of acetylenic glycol in which the main chain has 12 or more carbonatoms, and polyoxyalkylene alkyl ether (C), has excellent initialfilling characteristics and continuous printing stability, and even hasexcellent dissolution stability and a preservation stability, comparedto the ink supply system and the ink jet recording apparatus (eachcomparative example) which does not include the components and the inkabove. In addition, when acetylenic glycol (B) in which the main chainhas 10 or more carbon atoms is included in the ink, it was not foundthat the ink supply system and the ink jet recording apparatus providedwith the same had particularly excellent continuous printing stability(Examples 4B and 5B).

In addition, the reference examples will be studied, but the studydescribed below does not limit the scope of the present invention atall. The ink in the reference example 1B had the deaeration processingpartially performed thereon and included 5.5 ppm of dissolved nitrogen.In addition, the ink in the reference example 2B had the deaerationprocessing sufficiently performed thereon and included 1.4 ppm ofdissolved nitrogen. Here, the ink which almost does not perform thedeaeration processing, that is, the ink which is almost not deaeratedhas 5 ppm or greater of dissolved nitrogen, for example, and the inkwhich does not perform the deaeration processing at all, that is, theink which is not deaerated at all has 7 ppm or greater of dissolvednitrogen, for example (in each example and each comparative example, thedeaeration processing is not performed at all). Any of the referenceexamples has far less than 7 ppm of dissolved nitrogen. In this manner,in a case of the ink in which dissolved air (bubbles) is (relatively)low, even when the alkylene oxide adduct (A) of acetylenic glycol inwhich the main chain has 12 or more carbon atoms is not included, theinitial filling characteristics and the continuous printing stabilityare excellent. In other words, as the ink storage container in which theatmosphere and the ink are in contact with each other is not used, or asthe deaeration processing is performed, it was found that the problem(any one of the initial filling characteristics and the continuousprinting stability) to be solved by the present invention does not existin the ink which includes almost no air (bubbles).

1. An ink composition for ink jet recording, comprising: an alkyleneoxide adduct (A) of acetylenic glycol in which a main chain has 12 ormore carbon atoms; acetylenic glycol (B) in which a main chain has 10 ormore carbon atoms; and polyoxyalkylene alkyl ether (C).
 2. The inkcomposition for ink jet recording according to claim 1, wherein an HLBvalue of the polyoxyalkylene alkyl ether (C) is 12 to
 16. 3. The inkcomposition for ink jet recording according to claim 1, wherein thealkylene oxide adduct is an ethylene oxide adduct.
 4. The inkcomposition for ink jet recording according to claim 1, wherein a massratio between a content of polyoxyalkylene alkyl ether (C) and a totalcontent of alkylene oxide adduct (A) of acetylenic glycol in which themain chain has 12 or more carbon atoms and acetylenic glycol (B) inwhich the main chain has 10 or more carbon atoms is 0.10:1.0 to0.50:1.0.
 5. The ink composition for ink jet recording according toclaim 1, wherein an HLB value of the alkylene oxide adduct (A) ofacetylenic glycol in which the main chain has 12 or more carbon atoms is8 to
 15. 6. The ink composition for ink jet recording according to claim1, wherein an HLB value of the acetylenic glycol (B) in which the mainchain has 10 or more carbon atoms is equal to or less than
 4. 7. The inkcomposition for ink jet recording according to claim 1, furthercomprising a coloring agent.
 8. The ink composition for ink jetrecording according to claim 1, further comprising an organic solvent.9. An ink supply system, comprising: an ink storage container in whichthe atmosphere and the ink can be brought into contact with each otherand which stores the ink according to claim 1; a print head whichdischarges the ink; an ink supply path which connects the ink storagecontainer and the print head to each other, and in which the ink flowsto the print head from the ink storage container; and a filter (D) whichis provided in the ink supply path.
 10. The ink supply system accordingto claim 9, wherein an average pore diameter of the filter is equal toor less than a nozzle diameter of a nozzle of the print head.
 11. Theink supply system according to claim 9, wherein a plurality of filters(D) are provided in the ink supply path.
 12. The ink supply systemaccording to claim 9, wherein a material of the filter (D) is a resin.13. An ink jet recording apparatus, comprising the ink supply systemaccording to claim 9, wherein the ink supplied to the print head fromthe ink storage container is discharged toward a recording medium fromthe print head and recording is performed.